Enclosed precision switch



G- WINTRISS ENCLOSED PRECISION SWITCH Filed Oct. 4, 1960 July 16, 1963 IDOUBLE 63 6t THROW 22 OVERLAP 58 AT TOR NEYS SEQUENTIAL DO B E THROWUnited States Patent Ofihce 3,098,141 ENCLOSED PRECISION SWITCH GeorgeWintriss, Carversville, Pa. Filed Oct. 4, 1960, Ser. No. 60,378 7Claims. (Cl. 200-159) This invention relates to electric switches andmore especially to switches having contacts in a closed and sealedchamber.

It is an object of the invention to provide an improved electric switchhaving high capacity and much longer life than other switches. It isanother object to provide an improved switch in which the contacts areenclosed in a sealed chamber filled with gas or liquid for eliminatingor reducing any arcing of the switch contacts.

The invention is constructed so as to obtain silent, precision operationwith a short stroke; and the parts are shaped and correlated in such away that the invention may be used for extremely small switches. Thesealed feature makes the switch explosion-proof.

Another object is to provide a switch, of the character indicated, inwhich the contacts are located in position to obtain sequential closingof the respective circuits of the switch. In the preferred construction,the contacts are leaf springs and the switch has a plunger consisting ofa ball which wipes the contacts so as to maintain clean surfaces, andwhich rolls to some extent on the contacts so that different areas ofthe ball touch the contacts at different times. This maintains thesurface of the ball in a clean condition and equalizes any wear over thesurface of the ball. The switches of this invention are particularlysuitable for automatic controls, for many industrial and domestic uses,in missiles and electronic apparatus requiring precision switching, suband microrniniature switches, for either rotary switching or pushbuttonswitching.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views;

FIGURE 1 is a side elevation of a switch embodying this invention andmade in capsule form;

FIGURE 2 is a greatly enlarged sectional view on the line 22 of FIGURE1, but showing the switch installed in a holder;

FIGURE 3 is a sectional view on the line 3-3 of FIG- URE 2;

FIGURE 4 is a sectional view on the line 4-4 of FIG- URE 3;

FIGURE 5 is a diagrammatic, reduced-scale elevation of the switch andholder shown in FIGURES 2 and 3, and showing rotary cam means foroperating the switch;

FIGURE 6 is a diagrammatic view of a modified form of the invention; and

FIGURES 7-10 are diagrammatic views showing modified forms of theinvention.

FIGURE 1 shows a switch having a housing 10 made of electricalinsulating material and with a metal shell 11 covering most of theoutside of the housing 10. The contacts are enclosed in a chamber withinthe housing 10; and this chamber is closed and hermetically sealed inits upper end by a diaphragm 12. Conductors extend through the bottom ofthe housing 10 and have short extension portions 14 at the lower end ofthe housing 10 for connection with the circuits in which the switch isto be used.

The switch shown in FIGURE 1 is a unitary capsule construction which canbe inserted into a socket of control equipment in which the switch is tobe used. In the preferred construction there are lugs 16 extending fromthe shell 11 for holding the switch capsule in assembled 3 ,098,141Patented July 16, 1963 relation with the structure into which it isinserted and there is another lug '17 which serves as a key.

FIGURE 2 shows a portion of the interior of the housing 10. There is achamber 20 within the housing 10; and this chamber is preferably ofgenerally cylindrical cross section but with channels along its insidewall for receiving leaf-spring conductors 22. It is these leaf-springconductors 22 which extend through the bottom of the housing and whichhave the extensions 14 at their lower ends. For a portion of the heightof the chamber 20, there is a center cup 24 which holds the springconductors 22 securely clamped against the walls of the housing 10; andthe cup 24, spring conductors 22 and housing 10 are integral so as tocompletely seal the lower end of the chamber 2%).

FEGURE 3 shows the way in which the extensions 14, at the lower end ofthe housing 10, extend radially outward and downwardly in channels 26formed in the lower end of the housing 10 and providing clearance forthe contact extensions 14. When unrestrained, these extensions 14project some distance below the housing 10, as indicated in dottedlines, but they are resilient and are pressed upwardly into the channels26 when the housing 10 is pushed down into a socket 30 in a holder 32.The key 17 fits into a keyway 31.

There are fixed conductors 34 in the bottom of the socket 30 for contactwith the extensions 14 of the switch capsule. Each of these conductors34 extends upwardly in the holder 32 and then outwardly into a recess 38at the upper part of the holder 32. A terminal screw 40 in each of therecesses 38 extends through the conductor 34 and clamps a wire 42 to theconductor 34 for joining the conductor with an external circuit. Onlyone of the recesses 38 and terminal screws 40 are shown in FIG- UR 3 butit will be understood that there are others at different locationsaround the switch capsule, as indicated in FIGURE 2.

In the construction shown in FIGURES 2 and 3 there are four springconductors 22 and corresponding terminal screws 46; and there is also acenter contact 46 in the bottom of the cup 24. A special contact andconductor 50, in the bottom of the socket 30, is provided for connectingthe center contact 46 with an external circuit, and is an extension ofone of the conductors 34.

The switch has a plunger consisting of a metal ball 54 supported by a.circular upper end portion 56 of a spring 58. The lower end of thisspring 58 extends across and touches the inner end of the center contact46. Thus there is always a circuit between the ball 54 and the centercontact 46.

The upper portion of the chamber 20 is of larger diameter than theoutside diameter of the cup 24. This provides clearance behind thespring conductors 22 so that they can be displaced radially outward fromthe positions shown in FIG RE 3. The diameter of the ball 54 is slightlygreater than the distance between the spring conductors 22. Downwardmovement of the ball 24, therefore, causes the ball to touch the springconductors 22 and to bend them outwardly. The resistance of the springconductors 22 to bending provides pressure be tween them and the surfaceof the ball with which they contact. The upper ends of the springconductors are preferably shaped to provide them with concave faceshaving radii of curvature substantially equal to the radius of the ball54. These concave faces provide movable contacts 62 of the switch.

If the switch is to be used for opening a circuit as the ball 54 isdepressed, then the contacts at the upper ends of the spring conductors22 must be shaped as shown in FIGURE 6. A normally-closed circuit, whichis to be opened by downward movement of the ball 54, is pro vided with acontact 63 which projects radially inward from the spring conductor 22at an elevation which is above the maximum diameter of the ball 54 andout of contact with the ball when the ball is displaced downwardly intothe dotted-line position shown in FIGURE 6. The inner face of the springconductor 22 below the contact 63 is preferably covered with electricalinsulating material 63a so that displacement of the ball into contactwith the spring conductor 22 below the contact 63 can not close thecircuit. Various combinations of single-pole, double-throw switcheffects, with and without overlap of the closing of the circuits, can beobtained by having contact surfaces 63 of different lengths along thespring conductors 22 and at different elevations relative to oneanother.

At the upper end of the switch capsule there is a diaphragm 12. Thisdiaphragm is made of flexible material such as a plastic material havingphysical and dielectric strength, thermal range and chemical resistance,similar to polyesters, synthetic rubbers, polychemicals orfluorocarbons.

The diaphragm 12 has a bead 66 around its circumferential edge and thisbead 66 is held in place by a rolled-over edge 68 at the upper end ofthe shell 11. The diaphragm 12 is bonded to the shell 11 by cement, orin any other suitable manner. This construction with the bead 66 androlled-over edge 68 is merely representative of a hermetic seal betweenthe circumference of the diaphragm 64 and the metal shell or housing ofthe switch.

The height to which the ball 54 is raised by the spring 58 is limited bythe diaphragm 12. The switch can be made so that the ball is above allof the contacts 62 when in its fully raised position. With such aconstruction, the circuits of all of the spring conductors 22 are open.In the construction illustrated, however, the left-hand spring conductor22 is made high enough so as always to touch the ball 54. This gives theswitch a normally-closed circuit from the left-hand spring conductor 22to the ball 54 and through the spring 58 to the center contact 46. Ifthe switch capsule is made without any center contact 46, and anormally-closed circuit is desired, then two of the spring conductors 22can be made high enough always to touch the ball 54.

In the preferred construction, the posite spring conductors 22 arealways made of difierent height so that when the ball 54 touches thehigher one of the spring, conductors 22, it will tend to pivot aboutthat point of contact as it moves downwardly into position to touch theoppositespring conductor 22. This causes a rolling action of the ball 54which wipes the contacts 62 and which also causes different areas of theball to touch the contacts 62 on successive operations of the switch.This equalizes any wear of the surface of the ball 54.

The shell 11 has small lugs 16, which may be made of material displacedfrom the metal of the shell 11, and which extend outwardly beyond theedge of the socket 30. A cover 76 fits over the holder 32 and has anopening for receiving the upper end of the shell 11. This cover 76 fitssnugly around the outside of the shell 11 and holds the lugs 16 downagainst the holder 32 to keep the switch unit pressed down in the socket30. The cover 76 has recesses providing clearances for the lugs 16, butthis clearance may be provided in the holder 32, if desired;

The cover 76 extends across the recesses 38, and is secu-red to theholder 32 by screws 80 extending through openings in the cover 76 andthreading into sockets in the holder 32.

FIGURE 5 shows the holder 32 mounted in position that disposes theswitch with its longitudinal axis in a horizontal position. The centerportion of the concave diaphragm 64 is in the path of rises 90 and 91 ona cam 92. As the cam .92 is turned counter clockwise, the rise 90 firstdisplaces the diaphragm 64 toward the left in FIGURE 5 to operate theswitch, and as the cam is turned further, the rise 92 causes turtherdis]? diametrically opof the diaphragm 64 to operate other contactswithin the switch. The cam 92 may be oscillated back and forth orrotated in one direction depending upon the desired sequence ofoperation. A single rise is used when the switch has only one displacedoperating position.

From the description it will be apparent that the switch can be madewith a normally-closed circuit which is opened by the cam 92, or with anormally-open circuit which is closed each time the cam 92 displaces thediaphragm, or with both kinds :of circuits as will be described forFIGURE 9.

It will also be apparent that the switch can be made to operatedifferent circuits by having the necessary number of spring conductors22 (FIGURES 2 and 3) around the inside wall of the housing 10; and thatthese circuits can be closed simultaneously or in sequence, dependingupon .the length of the respective spring conductors.

FIGURE 7 shows a modified form of the invention which is in effect asingle pole, single throw switch in which the ball 54 touches contacts62 at the upper ends of leaf spring conductors 22. The contacts 62 areat the same level.

FIGURE 8 shows a modified construction in which the left-hand conductor22 has a contact 96 extending to a higher level than the contact 6-2 atthe right-hand conductor 62. In FIGURE 8 the spring 58 is part of thecircuit, and as the ball 54 moves downwardly in position to touch thecontact 96, a circuit is established between that contact and thecontact 46 at the bottom of the housing.

As the ball 54 continues its downward movement, a second circuit isestablished when the ball touches the contact 62. The contact 96 is longenough so that the ball touches it during the entire downward movementof the ball. This switch of FIGURE 8 gives sequential operation.

FIGURE 9 shows a construction in which the switch is in effect adouble-throw switch. With the hall 54 in its uppermost position, ittouches the contact 62 on the left-hand conductor 22 and establishes acircuit through the spring 58. As the ball 58 moves downwardly, it movesaway from the contact 62 at the upper end of the conductor 22 andtouches the contact 62 of the right-hand conductor 22 thus establishingan alternate circuit with the spring 58.

FIGURE 10 shows a modification of shown in FIGURE 9. Long contacts 98are used on both of the leaf spring conductors 22 so that the ball 54continues to touch contact 98 on the left-hand conductor 22 for at leasta portion of its travel after having moved downwardly far enough to alsotouch the contact 98 on the right-hand conductor 22.

The preferred construction of the invention has been illustrated anddescribed, but changes and modifications can be made and some featurescan be used in different combinations without departing from theinvention as defined in the claims.

I claim:

1. A switch including a housing enclosing a chamber with resilientcontacts confronting one another across the chamber, a plunger moveableaxially in the chamber into an out of con-tact with said contacts, thecontacts being positioned axially in the chamber so that. the plungertouches one before it touches the other during its axial movement towardthe contacts, said plunger being loose and rotatable in the chamberabout an .axis on which it is turned by friction against one contactbefore touching the other contact whereby contacting areas of theplunger are diiferent for successive operations of the switch, theplunger being a ball, and the switch including also a helical springholding the ball at one end of the chamber, said resilient contactsbeing leaf springs of different lengths.

Q. The switch described the construction in claim 1, and in which theretouch the ball when the is an upper contact in position to ball is inits uppermost position.

3. The switch described in claim 1, and in which the ball is movablethrough a stroke long enough to move away from said upper contact, andthere is a diaphragm closing the chamber above the ball, and the uppercontact is below the lowermost position of the diaphragm as saiddiaphragm depresses the ball.

4. The switch described in claim 2, and in which the contacts are theupper ends of leaf springs that serve as conductors and that extendlengthwise along the sides of the chamber, and the leaf spring for theupper contact has electrical insulation on a face that confronts theball.

5. A switch including a housing enclosing a chamber that has a lowerportion of reduced cross section and an upper portion of larger crosssection, resilient conductors extending upwardly along the wall of thechamber where said chamber is of reduced cross section, the resilientconductors extending longitudinally into the upper portion of thechamber with clearance from the wall, and a center element in the lowerportion of the chamber clamping the resilient conductors against thewall of the chamber, contacts at the upper ends of the conductors andconfronting one another, and a plunger in the upper end of the chamberremovable into position between the confronting contacts at the upperends of the resilient conductors.

6. A switch including a housing enclosing a chamber that has a lowerportion of reduced cross section and an upper portion of larger crosssection, resilient conductors extending upwardly along the wall of thechamber where said chamber is of reduced cross section, the resilientconductors extending longitudinally into the upper portion of thechamber with clearance from the wall, and a center element in the lowerportion of the chamber holding the resilient conductors against the wallof the chamber, contacts at the upper ends of the conductors, and aplunger in the upper end of the chamber removea-ble into positionbetween the upper ends of the resilient conductors, the center elementbeing a cup with its open end upward and its lower end closing the lowerend of the housing, the plunger being a ball having a diameter largerthan the spacing between confronting conductors on opposite sides of thechambers, and the switch including also a spring in the cup extendingupwardly above the cup and holding the ball at a normally elevatedposition in the chamber above the level of at least some of thecontacts.

7. The switch described in claim 6, and in which the cup is ofelectrical insulating material and it has a contact extending throughits bottom wall, and the spring is made of metal and forms an electriccircuit from the ball to said contact in the bottom of the cup.

References Cited in the file of this patent UNITED STATES PATENTS1,215,423 Spangler Feb. 13, 1917 2,451,176 Schellman Oct. 12, 19482475696 Cornish July 12, 1949 2,526,061 Batcheller Oct. 17, 1950

1. A SWITCH INCLUDING A HOUSING ENCLOSING A CHAMBER WITH RESILIENTCONTACTS CONFRONTING ONE ANOTHER ACROSS THE CHAMBER, PLUNGER MOVEABLEAXIALLY IN THE CHAMBER INTO AN OUT OF CONTACT WITH SAID CONTACTS, THECONTACTS BEING POSITIONED AXIALLY IN THE CHAMBER SO THAT THE PLUNGERTOUCHES ONE BEFORE IT TOUCHES THE OTHER DURING ITS AXIALL MOVEMENTTOWARD THE CONTACTS, SAID PLUNGER BEING LOOSE AND ROTATABLE IN THECHAMBER ABOUT AN AXIS ON WHICH IT IS TURNED BY FRICTION AGAINST ONECONTACT BEFORE TOUCHINGG THE OTHER CONTACT WHEREBY CONTACTING AREAS OFTHE PLUNGER ARE DIFFERENT FOR SUCCESSIVE OPERATIONS OF THE SWITCH, THEPLUNGER BEING A BALL, AND THE SWITCH INCLUDING ALSO A HELICAL SPRINGHOLDING THE BALL AT ONE END OF THE CHAMBER, SAID RESILIENT CONTACTSBEING LEAF SPRINGS OF DIFFERENT LENGTHS.